Mast



Jan. 24, 1967 J. C. BAMFoRb MAST E Sheets-Sheet l Filed July 20, 1965Car-WM Jan. 24, 1967 J. c. BAMFORD MAST 3 Sheets-Sheet 2 Filed July 20,1965 Asem' Jan. 24, 1967 1. c. BAMFoRD 3,300,051

MAST

Filed July 20, 1965 5 Sheets-SheetI 5 WWW HGEMT United States Patent O3,300,061 MAST Joseph C. Bamford, Uttoxeter, England, assignor to J. C.Bamford (Excavators) Limited, Lakeside, Rocester, England, a Britishcompany Filed July 20, 1965, Ser. No. 473,461 Claims priority,application Great Britain, July 23, 1964, 29,637 64 2 Claims. (Cl.212-144) This invention relates to masts and has for its main object tovprovide a new or improved f-orm of mast which can be collapsed andstowed when not in use.

With this main object in view, according to the invention we provide amast comprising two or more tubular sections which are telescopically.arranged one within another, the or each section above the lowermostbeing fitted as a piston in the section next below and means beingprovided for supplying air under pressure to the interior of the mastand releasable locking means being provided between the or each pair ofsections to hold the sections in their extended relative positions.

In order to provide for collapsing for storage or transport, thelowermost section of the mast may be pivotally mounted about ahorizontal axis upon a base member so that the mast may be pivoted aboutsaid axis to lie in a horizontal or substantially horizontal plane withall the other sections telescoped therein.

Preferab1y,'a boom is connected to the uppermost section to projecttransversely therefrom when the mast is extended.

To withstand the heavy load imposed on the mast when lifting heavyweights the locking means provided must be strong and preferably thelocking means between the or each pair of sections comprises a pluralityof locking elements spaced apart around the annular space between the oreach pair of telescoped sections and each locking element comprises alocking plate, secured to the exterior of the inner section of the oreach pair of sections, and having a recess extending substantiallytangentially to said inner section from a vertical edge of said lockingplate, and a locking piece slidably mounted on the outer section of theor each pair of sections for angular movement about the vertical axis ofthe mast from a disengaged position to an engaged position in which thelocking piece engages with said recess to prevent vertical displacementof the sections relative to each other.

Preferably each locking piece projects outwardly through a slot formedin said outer section and each l-ocking piece is secured to a bandmember which extends around the periphery of the said outer section,whereby movement of all said locking pieces from their disengagedposition to their engaged position is achieved simultaneously.

The above described arrangement may be made portable by mounting thebase member upon a suitable vehicle and the base member may incorporateslewing means for rotating the mast, When extended, about a verticalaxis to traverse the boom, or alternatively, the traversing of the boommay be provided by arranging a slewing ring on the uppermost section,the boom being connected to this ring for rotation about a verticalaxis.

The mast according to the present invention may be used in a variety ofapplications such as a portable television or radio mast and isespecially suitable for a portable crane.

A crane ernbodying the present invention will now be described in moredetail by way of example with reference to the accompanying drawings, itbeing appreciated that the scope of the invention is not limited tocertain specific details mentioned hereinafter.

ICC

FIGURE 1 is a side elevation of a crane embodying the present invention,mounted on a railway bogey and in its extended position,

FIGURE 2 is a part section, to an enlarged Scale, on the centre line ofFIGURE 1, showing the telescoped ends of the lower and intermediatesections,

FIGURE 3 is a part sectional plan view on the line 3- 3 in FIGURE 2,and,

FIGURE 4 is a side elevation of another example of a crane embodying thepresent invention, mounted on a lorry and in its stored position.

In this arrangement the mast, which is indicated generally at 10 inFIGURE 1, comprises three sections, there being a lowermost section 11,an intermediate section 12 and an upper section 14 each made from steeltubes and of appropriate diameters so that the intermediate section 12is telescopically slidable within the lowermost section 11 and theuppermost section 14 is telescopically slidable within lthe intermediatesection 12.

The external diameter of the intermediate section 12 is such as toprovide an annular clearance 20 (see FIG- URE 2) between its wall andthe interior of the lowermost section 11 and a similar arrangementoperates for providing an annular clearance between the uppermostsection 14 and the interior wall of the intermediate section 12 and eachof the intermediate and uppermost sections 12 and 14 respectively hasits lower end 15 and 16 respectively fitted with an annular ring (whichis shown at 18 in FIGURE 2 in the case of the intermediate section 12)the external'diameter of which is such that it slidably engages theinterior wall of the section within which it slides and the underside ofthis ring is fitted with an annular Sealing ring (which is shown at 19in the case of the intermediate section 12) of suitable material such asneoprene to form an air-tight seal with the interior wall of the sectionin which it slides.

Thus the uppermost and intermediate sections 14 and 12 respectively havesliding engagement as pistons within the interior of the intermediateand lowermost sections 12 and 11 respectively and the top end 17 of theuppermost section 14 is completely closed so that when compressed air isintroduced into the interior of the mast 10 when in its collapsedposition, the intermediate and uppermost section 12 and 14 respectivelywill be elevated ydue to the air pressure so as to extend the mast 10 toits full height.

It is necessary to provide suitable locking means 'between each pair ofsections when in the fully extended position to lock the sectionsrigidly together for operation of the crane and the following is adescription of a preferred locking mechanism for locking the sectionstogether. The locking means employed must be strong in order towithstand the heavy loads imposed when lifting heavy weights. Suchlocking means is employed between the uppermost and intermediatesections, and the intermediate and lowermost sections. For convenienceof description only the locking means between the intermediate section12 and the lowermost section 11 will be described and it should beunderstood that the locking means between the uppermost section 14 andthe intermediate section 11 are identical.

Referring to FIGURES 2 and 3, in the annular space 20 between theintermediate section 12, which is the inner section and the lowersection 11, which is the outer section, the ,inner section 12 hassecured to its exterior, a number of locking elements, indicatedgenerally at 21, each of which comprises a plate 22 of rectangular formarranged with its major axis vertical and having a recess 23 extendinginwardly from one of the longer side edges of the plate and theselocking elements 21 are secured to the exterior of the inner section 12at spaced apart positions around the circumference.

The outer section 11 at a position near its upper end, has a number -ofslots 24 in its wall, these slots 24 corresponding in number to theplates 22 on the inner section 12 and being spaced apartcircumferentially. A locking piece 25 is slidably mounted in each slot24 so as to be capable of an angular movement about the vertical axis ofthe mast from a disengaged position to an engaged locking position asshown in FIGURE 3. 1

All the locking pieces 25 project through the slots an are secured to acommon circular 'band 26 which extends around the whole of the peripheryof the outer section 11, this band 26 being capable of being fixed ineither of two positions by means of a peg 27 passing through a hole 36in a lug 28 projecting radially from the band, such peg 27 beingengageable in either one of two holes 30 and 31 spaced apart in abracket 29 secured to the exterior of the outer section 11.

The aforesaid locking plates 22 are disposed adjacent the lower end oflthe inner section 12 and when this section 12 is extended upwardly thelocking plates 22 reach a position where they come into register withthe circle of slots 24 and locking pieces 25 carried by the outer member26 and at this stage the band 26 carrying the looking pieces 25 is movedfrom its disengaged position into the position which causes the lockingpieces 25 to slide into the recess 23 in the locking plates 22, the band26 being then secured in this position by inserting the peg 27 throughits lug 28 and into the second hole 31 of the aforesaid bracket 29 onthe outer section 11.

Thus vvith this arrangement, the two sections are locked togetheragainst relative axial displacement, and together with the exactlysimilar locking means between the uppermost section 14 and theintermediate sections 12 the mast is locked in its extended position.

The boom 34 is mounted at the upper end 17 of the uppermost section 14and may be in the form of a tubular lattice boom having a crane hook 35which may be carried on a travelling carriage 36 moving lengthwise ofthe boom 34 in generally known manner. The boom 34 may be pivotallyconnected as shown at 37 to a member 38 at the top of the uppermostsection 14 for lufling movement in a vertical plane. As 'shown in FIGURE1, the slewing or traversing of the boom 34 is obtained by mounting thecomplete mast 10 upon a base member 39 which is itself mounted forslewing about a vertical axis for the purpose of traversing the boom 34through anyl angle up to 360. ,V

Alternatively, the member 38 may be arranged as a slewing ring so as tobe rotatable about the vertical axis of the upper section for thepurpose of traversing the boom 34 through any angle up to 360.

The Ibase member 39 is mounted upon -a suitable vehicle such as arailway bogey 40 as shown in FIGURE 1 or alternatively on a crawlerItractor or other wheeled vehicle such as a trailer or tractor or lorry50 as shown in FIGURE 4 or other road vehicle for the purpose oftranspor-ting the complete crane in its collapsed state.

For collapsing purposes, the lowermost section 11 may be mounted asshown in FIGURES 1 and 4 for pivotal movement about a horizontal axis,such axis being spaced 0 A, L, LEVINE, M. L. AJEMAN,AssismmExaminef-s. H

a short distance above the lower end of the lowermost section 11 and,for example, there may be a pair of spaced apart pillars 42 supportingat their upper ends, a horizontal axis in the form of trunnions 41 forengagemen't by pivot pins 43 secured to the lowermost section 11, whichis the outer section and the pivotal movement may be obtained by aPneumatic ram 45 or rams connected between the base member 39 and thelowermost section 11.

When the mast is in the collapsed state as shown in FIGURE 3, it may bepivoted about its horizontal axis to lie in a substantially horizontalposition and the boom 34 is also pivoted so as to lie in asu'bs-tantially horizontal position above the collapsed mast 10.

What I claim then is: i

1. A tower mast for a crane comprising a lower tubular section closed atits lower end, an intermediate tubular section open at both ends andslidable telescopically within the lower section, an upper tubularsection closed at its top en-d and slidable telescopically within theintermediate section, means for supplying compressed air into theinterior of themast, a first annular Sealing ring secured to the lowerend of the intermediate section and` having air tight Sealingengagernent with the interior of the lower section, a second annularsealing ring secured tothe lower end of the upper section and having airtightv sealing engagement with the interior of the intermediate section,there being an annular space between -the lower and intermediatesections and 'between the intermediate and upper sections, and lockingmeans for locking each two adjacent sections rigidly together located insaid annular Spaces, each such locking means comprising a set of lockingplates secured in spaced apart circumferen-- tial relationship to theexterior of the inner tubular section of the two anda corresponding setof locking pieces slidably mounted in spaced apart circumferentialrelationship on the outer section of the two, each such locking platehaving a recess engageable with one of said lockingl pieces.

2. A tower mast according to claim 1 wherein each cumferencel througheach one of which a locking piecev projects.v

References Cited by the Examiner UNITED STATES PATENTS 2,676,677 4/1954Anderson et al 254--93 X 2,895,622 7/1959 Sundin 212-55 X 3,168,3362/1965 Lawrence 212-144 X 3,194,411 7/1965 Durand 212-46 SAMUEL F.coLEMAN, Primary Examiner.

EVON C. BLUNK, Examiner.

1. A TOWER MAST FOR A CRANE COMPRISING A LOWER TUBULAR SECTION CLOSED AT ITS LOWER END, AN INTERMEDIATE TUBULAR SECTION OPEN AT BOTH ENDS AND SLIDABLE TELESCOPICALLY WITHIN THE LOWER SECTION, AN UPPER TUBULAR SECTION CLOSED AT ITS TOP END AND SLIDABLE TELESCOPICALLY WITHIN THE INTERMEDIATE SECTION, MEANS FOR SUPPLYING COMPRESSED AIR INTO THE INTERIOR OF THE MAST, A FIRST ANNULAR SEALING RING SECURED TO THE LOWER END OF THE INTERMEDIATE SECTION AND HAVING AIR TIGHT SEALING ENGAGEMENT WITH THE INTERIOR OF THE LOWER SECTION, A SECOND ANNULAR SEALING RING SECURED TO THE LOWER END OF THE UPPER SECTION AND HAVING AIR TIGHT SEALING ENGAGEMENT WITH THE INTERIOR OF THE INTERMEDIATE SECTION, THERE BEING AN ANNULAR SPACE BETWEEN THE LOWER AND INTERMEDIATE SECTIONS AND BETWEEN THE INTERMEDIATE AND UPPER SECTIONS, AND LOCKING MEANS FOR LOCKING EACH TWO ADJACENT SECTIONS RIGIDLY TOGETHER LOCATED IN SAID ANNULAR SPACES, EACH SUCH LOCKING MEANS COMPRISING A SET OF LOCKING PLATES SECURED IN SPACED APART CIRCUMFERENTIAL RELATIONSHIP TO THE EXTERIOR OF THE INNER TUBULAR SECTION OF THE TWO AND A CORRESPONDING SET OF LOCKING PIECES SLIDABLY MOUNTED IN SPACED APART CIRCUMFERENTIAL RELATIONSHIP ON THE OUTER SECTION OF THE TWO, EACH SUCH LOCKING PLATE HAVING A RECESS ENGAGEABLE WITH ONE OF SAID LOCKING PIECES. 